Drill grinder



E. C. OLIVER I DRILL GRINDER Aug. 12, 1941.

8 Sheets-Sheet l Filed March 7, 1939 ATTORNEY.

Aug. 12, 1941. c, o vg 2,252,303-

DRILL GRINDER Filed March 7, 1932 8 Sheets-Sheet 2 INVENTOR ATTORNEY. I

E. C. OLIVER DRILL GRINDER Aug. 12,1941.

Filed March '7, 1939 8 Sheets-Sheet 4 INVENTOR.

Afig. 12, 1941. Q QUVER 2,252,303

DRILL GRINDER Filed March 7, 1939 8 Sheets-Sheet 5- vim g INVENTOR. I1.5.2. 50 4 a o/n e/ ATTORNEY.

Aug. 12, 1941. E. c. OLIVER 0 DRILL GRINDER Filed March '7, 1939 8Sheets-Sheet 6 ATTORNEY.

1941- l E. 'c. OLIVER 2,252,303

' DRILL GRINDER Filed March 7, 1939 8 Sheets-Sheet 7 INVENTOR. 3 50 0 6.a l

ATTORNEY.

E.- C. OLIVER DRILL GRINDER Aug. 12, 1941.

Filed March 7, 19:59 8 Sheets-Sheet a INVENTOR. Er/o/ 6. O/I'V/ BYATTORNEY.

Patented Aug. 12, 1941 UNITED STATES ATENT OFFICE DRILL GRINDER,

. Edd 0. Oliver, Adrian, Mich.

Application March 7, 1939, Serial No. 260,344

Claims.

This invention relates to variable point drill grinder, the object ofthe invention being to provide a machine of such structure as to permitgrinding the points of twist drills to various chisel point angles andalso involving means providing for variation in clearance on the landsof the drill and thus adapting the machine for use in grinding drillpoints for different characters of metal to be drilled.

there being a positive relation between the position of the lands of thedrill during rotation in respect to the position of the grinding wheelas is hereinafter described irrespective of the angle of presentation ofthe drill.

A further feature and object of the invention is to provide a mechanismfor grinding a drill to provide a slightly rounded chisel pointhereinafter termed the point of web intersection to more readily permitthe drill to enter a center punch mark than has heretofore been securedwith the older type of drills.

The character of the drill point to be formed by the machine is shownand described in my U. S. Patent No. 1,467,491 of September 11, 1923 andthe machine embodying the invention herein described is similar to thedrill point grinder shown in my U. S. Patent No. 1,546,453 of July 21,19 26 but differs therefrom in many respects, principally in that it isadapted. to grind two, three or four lipped drills having points withinthe full range of point and clearance angles.

These and various other objects and novel features of the invention arehereinafter more fully described and claimed, and a machine embodying myinvention is shown in its preferred form in the accompanying drawings inwhich-- Fig. 1 is a plan view of the machine.

Fig. 2 is a front elevation of the machine.-

Fig. 3 is a vertical section of the machine taken on line 33 of Fig. 4.

Fig. 4 is a sectional View of the head of the machine taken on line-A--4 of Fig. 3.

Fig. 5 is a face elevation of a cam adjuster.

Fig. 6 is a. side elevation thereof.

Fig. '7 is a face view of a circular cam for varying the clearanceangle.

Fig. 8 is a side elevation thereof.

Fig. 9 is a diagrammatic view showing the cam face laid out in astraight line.

Fig. 10 is a face view of a twist drill as formed by the machine.

Fig. 11 is a section taken on line Iill of Fig. 4. i

Fig. 12 is an enlarged section through the cam adjuster taken on line3-3 of Fig. 4.

Fig. 13 is a face elevation of the chuck showing the gauge for the drillpoint and associated parts in the plane of line l3-l 3 of Fig. 1.

Fig. 14 is an enlarged section taken on line i4l4 of Fig. 3.

Fig. 15 is an enlarged view showing the train of gearing for driving thedrill rotating mechamsm.

Fig. 16 is an elevation showing the grinding wheel and relationship ofthe drill point thereto in the grinding operation.

Fig. 17 is a diagrammatic View of certain pulleys and the motor drivenbelt for driving the same.

Fig. 18 is an enlarged sectional view of the change speed. mechanism.

Fig. 19 is a section of a clutch mechanism.

Fig. 20 is a section taken on line 20-28 of Fig. 19.

Fig. 21 is an elevation of a convenient means for operating the camadjuster.

Fig. 22 is a section taken on line 22-22 of Fig. 20.

Fig. 23 is an elevation of a cam sleeve.

Figs. 24 and 25 are respectively an end and a side elevation showing thelands of the drill formed with more than two concentric areas atdifferent angles to the longitudinal axis of the drill.

Figs. 26 and 2 7 are respectively an end and a side elevation of thelands of the drill having the surface ground to provide two concentricareas at different angles to the longitudinal axis of the drill.

The machine, according to this invention, is so designed and constructedas to form the cutting end of a twist drill, a face view of a two lippeddrill being shown in Fig. 10 but, as hereinafter shown, the machine isadapted to form two, three or four lipped drills as may be desired. Inthe drill indicated in Fig. 10, the angle of the chisel point to thecutting edge of the lip is shown as being about degrees but this anglemay vary. As hereinafter described, the machine is adapted to form apoint angle of from 82 to 160 degrees and thus to secure a drill of thedesired cutting action for metals of various characters.

In the construction herein shown, the chuck I for carrying the drill isswingable on an are about a vertical axis cutting the point I2 of Fig.1, it being carried by a base plate 2 having a tongue riding in anundercut slot II) of arcuate form in the carriage or table 2. This tablewith the chuck therein is movable in a straight line by means of a screw3 operable by a handle 4 by rotation of which in one direction or theother, the drill is moved toward or away from the grinding wheel 5.

The grinding wheel, shown in the enlarged view Fig. 15, is of the ringtype and the drill is rotated by mechanism hereinafter described in thedirection shown by the arrow and the drill is positioned with thecutting edge of the land 6 of the drill in engagement with the wheel andthe point of web intersection is practically at the inner edge of thewheel so that as the drill is rotated the land is cut away to the rearfrom the cutting edge on an oblique helicoid to provide clearancepractically of equal extent clear to the point except that the pointitself is not ground away. Thus a hollow indicated at I in Fig. 10 isproduced in front of the chisel point 8 which increases in depth towardthe rear of the land due to the turning of the drill and the feeding inmovement of the grinding wheel. This form of drill point is fullydescribed in my U. S. Patent No. 1,467,491 of September 11, 1923.

The chuck I is mounted on a table that is movable on. a straight lineparallel with the axis of the shaft 9 of the grinding wheel as will beunderstood from Figs. 1 and 2 while the chuck is swingable through theare formed by the way I in the carriage 2 as heretofore stated. Thisswinging of the chuck varies the angle of the longitudinal axis of thedrill relative to the face of the grind ing wheel'and by varying theangle of the presentation of the drill to the grinding wheel the pointangle may be varied.

By means of the hand wheel 4, the carriage 2 is movable to bring theface of the drill to cutting position and for the purpose of correctlypositioning the drill, a movable gauge I I is provided, the upper end I2of which lies between the face of the grinding wheel and the chuck(which 1 may be freed from its driving mechanism as hereinafterdescribed) is turned by the handle [2a to position the cutting edge ofthe lip parallel with the gauge end I2. When so positioned, the plate 2is then moved to position the drill in engagement with the grindingwheel and the mechanism for rotating the chuck operates to turn thedrill to bring the successive lands to proper position for the grindingoperation by the wheel.

The general arrangement of the parts is shown more clearly in Fig. 3 inwhich there is a base or column I3 and in the bottom thereof is a motorI4 on the shaft of which is a pulley I5 having a belt I5 rotatable inthe direction shown by the arrows in Fig. 17 and riding over a pulleyI'I thence under a pulley I8 and over a pulley I9 driving the grindingwheel shaft 9, the pulley I8 driving the shaft 28 and the pulley I'Idriving the shaft 2 I.

In the construction shown, there is an arm 23 attached to the base andsupporting a tray 24 on which the head of the machine is mounted andwhich carries a support 25 for the slide 26 on which the carriage 2supporting the chuck is slidable by the screw 3. It is to be noted thatthe shaft for the screw passes through a bearing member 2'! and has aring flange 28 on the inside of the bearing member and the hub of thewheel contacts the outer face thereof thus fixing the screw shaft fromlongitudinal movement in the member 2'? which in turn is fixed to thecarriage 2 carrying the chuck and also to a cover plate 28a on the underside. Thus rotation of the screw in respect to the fixed nut 29 securedin the slide 25 moves the chuck. The drill 30 is placed in the chuck sothat the land of the drill lies across the V of the chuck jaws 3i and 32as shown in Fig. 13 and as the cutting edge of the lip may not be incorrect relation to the wheel, means is provided permitting manualrevolution of the chuck to bring the cutting edge to proper relationwith the gauge. The clutch 53 is then engaged with the driving mechanismhereinafter described and by the positioning of a drill at the innerperiphery of the ring grinding wheel as indicated in Fig. 15, the drillis turned so that the drill runs off the inner face of the grindingwheel and this action causes the chisel point of the web intersection tobe slightly rounded thereby permitting the drill to enter a center punchmark more readily than is the case with the drill formed by the machineshown and described in my U. S. Patent No. 1,546,453.

The chuck jaws are rotatable within the outer case shown at I in Fig. 1and there is an arm 33 extending from the rear end of the casing onwhich is an adjustable bracket 34 carrying an adjustable center point 35engaging the rear end of the drill 3S and thus drills of differentlengths may be mounted in the chuck. The jaws are driven by atelescoping shaft 36 having universal joints 3'! therein to secureflexibility. A portion of this shaft is shown in Fig. 1 and has a stub38 connected with a driving gear 39 at the one end as shown in Fig. 14and the opposite end has a stub shaft portion 40 in a housing 4Isupported by the chuck casing and on which is a beveled gear 42 drivinga beveled gear 43 mounted in the rear end of the casing for the chuck asshown in Fig. 15. Thus rotation of the shaft 35 will rotate the drillduring the grinding operation. This telescoping shaft and universaljoint structure permit the chuck to be swung in the groove It in thecarriage 2. The shaft is driven by the gear 39 as previously statedwhich meshes with an intermediate gear 44.

The driving element in Fig. 15 has the gears laid out in a line so thatthe drive for the telescoping shaft 36 will be readily understood. InFig. 14, it will be noted that the gear 44 has a short shaft 45supported in the head casting and the gear 44 meshes with a gear 46mounted on the shaft 41 which is integral with an enlarged portion 48.Fixed on the enlarged shaft portion 48 are the stepped gears 49, 50 andBI.

Also fixed on the shaft 48 is one member 52 of a jaw clutch, the othermember 53 of which is slidable longitudinally of the shaft 48, it havinga pin 54 extending through a slot provided therefor in the shaft 48. Thepin 54 passes through a shaft 55 slidable within the hollow end of theshaft 48 and extends therefrom to engagement with an eccentric cam 55.Rotation of the cam by the handle 51 and shaft 58 causes the clutchmembers 52 and 53 to be engaged or disengaged and by disengagement ofthe clutch elements the jaws of the chuck may be rotated to properlyposition the drill point relative to the gauge and then the clutch mayagain be engaged. This operation of the eccentric element 56 is by meansof an operator handle 51 extending to one side ofthemachine shown inFig. 14 whereby the shaft 58 carrying the eccentric 56 may be moved torelease the clutch against the tension spring 59 which, when free toact, holds the clutches in engagement. The engagementof the chuck withthe driving means is thus positive.

The gears 49, 50 and are respectively in mesh with the gears 66, BI and62 rotatable on a hollow shaft 63 and a clutch device is provided forengaging one or the other of the gears to the shaft which consists ofthe operating rod 64 slidable in the shaft 63 and having notches thereinfor engagement with the spring pressed pin 65, shown in Fig. 3, therebeing a notch for each gear.

This rod 64 has a pivoted latch member 66 at its inner end and has anendriding in a slot in the shaft 63 to engage a keyway provided in thehubs of the gears. By sliding the rod 64 one or the other of the gearsmay be fixed to the shaft by the latch. This arrangement adapts themachine for the grinding oftwo, three or four lipped drillsbut in thegrinding of any one of the drills, the cutting edges are broughtconsecutively to similar position for operation by the grinding wheel.The structure of the control means for the gears 69, 6I and 62 -is shownmore clearly in Fig, 14 from which it will be realized that the pawl orlatch member 66 is pivoted to the end of the shaft 64 and as will beseen in Fig. 18,.the latch member 66 has an angular face engaged by thespring pressed element 61 which tends to hold the latch member inposition. There is a spacing ring 6i] between the gear 69 and 6| and asimilar spacing ring 69* between the gear 6| and 62. These rings have aninside diameter fitting the shaft 63. This arrangement permits the latchelement to be depressed by the inner edge of the spacing rings at thenotches in the gear in moving from engagement with its way in one gearto position within the center of the other gear and to engage in thenotch therein. Means may be provided to indicate the position of theclutch element through movement of the rod 64 as, for instance, by gaugemarks 66 on the projecting end of the shaft 64.

While the grinding wheel is carried by the shaft 9 and rotates on theshaft axis, the said shaft is mounted in bearings II. The seats forthese hearings are eccentric to the axis of the shaft 9 and mountedwithin the quill 19. In other words, while the grinding wheel rotates onan axis, the wheel, as a whole, is caused to re- .volve about a centereccentric to its axis of rotation. Rotation of the quill thereforecauses an oscillation of the shaft 9 and consequent movement of thegrinding wheel relative to the drill point. which is held by the chuckto rotate on a fixed axis. This oscillatory movement of the grindingwheel is illustrated somewhat diagrammatically in Fig. 16.. In locatingthe lands of the drill, as heretofore stated, across the jaws of thechuck, the cutting edge of the land is located by the gauge and thegrinding wheel is then set into operation and as hereinafter shown, thegrinding wheel feeds toward the drill as the drill is being rotated and,thus the point of web intersection, due to the oscillation of thegrinding wheel, is relatively moved in respect to the inner edge 5 ofthe grinding wheel asthe wheel is moved into the work to the fullextent. This causes the drill to be undercut to the rear of the land andadjacent the web intersection as indicated at I in Fig.10.

The feed of the grinding wheel is secured by means of an adjustable cam99 which is of ayring form and is mounted on the quill I9 as shown inFig. 3. This adjustable cam is shown in Figs. 7, 8, 9, 11 and 12. Thiscam consists of a split ring 9| shown in face view in Fig. 7 having aperipheral' face portion 92 shaped as indicated in the diagram Fig. 9,it having a straight portion 93 parallel with the base from A to D,.asharp outwardly inclined face portion 94 from D to C and an inwardlyinclined portion 95 of less angle than 99 extending from C to B and thenfrom B to A a sharply inclined portion 96. This cam is secured to thequill as by screws or pins 91, 98

- and 99, the screw 99 being some distance peripherally from the slot I09 between adjacent ends of the cam. Thus, as the quill is rotated, itrides in engagement with an adjustable plug IliI, the location of whichis shownin Fig. 3. This plug, as shown in Fig. 3, is adjustable byhaving a threaded end I92 in the casing part therefor and has a slot I63in which there is a pin I99 to hold the same from rotation and a setscrew I65 to hold the same from longitudinal movement. The grindingwheel is spring pressed to the right in Fig. 1 by the spring I01engaging the pin I96 which in turn engages the'side face of the gear E99secured to the quill. This spring holds the cam face 99 in engagementwith the adjustable plug Hit and due to the configuration of the camshown in Figs. '7, 8 and 9 the grinding Wheel is moved into the work andagainst the tension of the spring I91 which retracts the wheel from theWork when the portion 93 of the cam is in engagernent with the plug It".An adjusting screw I96 is provided to secure the desired spring tension.

The spring, as the revolution is completed, moves the grinding wheelaway from the drill at the completion of the grinding at which time thesharply inclined portion 96 of the cam rides the adjustable plug IiiI.This portion 99 of the cam provides for a quick retraction of thegrinding wheel thus preventing engagement of the next land of the drilltherewith. During the time the cam portion 93 engages the plug IIJI thedrill has been turned to position the next land of the drill forgrinding. This portion 93 of the cam permits the grinding wheel toremain in retracted position and the cam is so rotatively positionedthat the portion 94 begins to feed the grinding wheel forward into thework. The end of the cam ring at 99 is free to be adjusted to vary theposition of the angular face 95 to thereby increase or decrease theextent of the feeding movement of the wheel as it passes off the land informing the hollow 1 at the point of web intersection. This end 96 ofthe cam is adjusted by a cam element I09 rotatably supported in a recessprovided in the flange of the gear 12. This cam member I99 has aperturesin the enlarged head thereof to receive an adjusting pin for the turningof the same and the inner face of the head portion has a circular camface IIEI on which a pin III engages at one end, the opposite engagingend 96 of the cam ring 99 as will be understood from Figs. 9 and 11.

Adjustment of the cam is provided through removal of the cap plate I I3at the top of the head and the gear 72 has an aperture therein throughwhich the pin I I2 may be introduced to rotate the member I69 and thusto vary the angle of the face portion 95 of the cam ring 99.. Therotatable adjusting cam I 09 is held in the adjusted position by aspring pressed centering pin I99 on the under side directly opposite thepoint of introduction of the adjusting element H2 which is introducedthrough the aperture I I9. of the gear "I2 as in Fig. 12. The clearanceangle may thus be varied by use of the cam 93 and likewise the depth ofthe cut of the wheel as the point of web intersection of the drill movesoff the inner face of the grinding wheel by reason of oscillation of thequill.

Thus a lip or land of the drill is ground through one revolution of thequill and a new land is brought to grinding position at each revolutionof the quill. The wheel is rotated at comparatively high speed due toits belt drive by the pulley I9 while the quill is rotated at a slowspeed and so timed in its movement that the point of web intersectionpasses off the inner periphery of the grinding wheel. The position ofthe portions A, D, C and B of the cam 90 in respect to the drill pointare indicated in Fig. 10 from which it will be seen that the angle A, D,etc., of the cam is twice the same angle on the drill so that each landis formed by a complete revolution of the cam. In a three lipped drill,the angles A to D to C on the cam would be three times and with a fourlipped drill four times the same angle on the drill diagram.

It is thus to be seen that a drill of a two, three or four lipped typemay, by choice of the driving gears 60, 6| or 62 through the respectivegearing 49, 50 or be rotated at a speed to bring the successive lips ofthe drill to the starting position in respect to the grinding wheel andin timed relation with the feed of the grinding wheel toward the drillin order that each land may be ground with the proper clearance.

It will be realized that the chuck, while adapted to rotate the drill,holds the drill during the grinding in a fixed position in respect tothe grinding wheel and that the grinding wheel requires to be fed intothe work as the work is turned. This feed-in movement of the grindingwheel is provided by a cam which is variable as hereinafter shown inorder that the face of the drill may be formed with different clearancesfor drills required for different characters of metal.

The grindin wheel is mounted on the shaft 9 which is rotatable by thepulley I9 by means of a belt I6 which, as previously stated, also drivesthe pulleys I! and I8. Incidentally, it is pointed out that the pulleyI1 is here shown as driving the water pump 69 which is only used withwhat is known as wet machines. The pulley, however, may be used forother than the wet machines. The quill has the bearings 1| at oppositeends of the quill for supporting the shaft 9 and the quill is driven bya gear I2 which is bolted to a flange provided on the quill as shown andthe gear I2 is in mesh with a gear I3 keyed to the shaft 63 whichsupports the stepped gears 60, 6I and 62.

The entire train of gearing is not shown in Fig. 3 due to the varyinglocation of the gears but the drive for the gear, shaft 63 and shaft 36leading to the chuck is laid out in line in Fig. 15. From this View itwill be seen that the quill I9 has its gear I2 meshing with the gear I3on the shaft 63 and there is a companion gear I3 loose on the shaft 63and driven by a pinion I4 on the shaft point when the cutting edge of aland of the drill is'presented for the grinding operation at which timethe grinding wheel is again fed into the work. It 'is thus importantthat the position of the cam rotatively be in timed relation with therotation of the drill and further it will be realized that as one drillhas been ground, the ground drill must be removed from the chuck and anew drill positioned therein and that the chuck be then turned toposition the cutting edge of the land in respect to the gauge end I2shown in Fig. 13.

To so manually rotate the chuck elements to properly position the drillfor the grinding operation, it is necessary that the chuck be freed fromthe driving mechanism and when it again is to be driven it must be intimed relation with the rotation of the cam. For this purpose, I providea clutch member 11 by means of which the gear I3 may be connected ordisconnected with the gear I3. The clutch mechanism is shown in Figs.19, 20, 22 and 23 in which the gear I3 is shown. The arrow adjacent thetoothed periphery indicates the direction of rotation and the gears I3and I3 in Figs. 19, 20 and 22 which views are taken on the opposite sidefrom that shown in Fig. 15. The clutch means includes a spring pressedlever H4 carried by a shaft H5 mounted below the cap H6. The operatinglever H1 is attached to a shaft H8 and this shaft has a cam end I I9within the cap. The cam end H9 has opposed flat surfaces I20 and I2I ata right angle one to the other and the distance of the center ofrotation of the cam end is nearer to the flat face I2I than to the flatface I20 at a right angle thereto. In the position shown in full linesin Fig. 19, the flat face I2I is in engagement with the end I22 of thelever H4 and when the lever I I1 is turned to the dotted line positionthe face I29 of the cam H9 engages the face of the portion I22 of thelever H4. By the turning of the lever I I! to the full line position thecam plate I23 carried by the lower end of the lever I I4 as shown inFig. 22 is in position to ride into the cam slot I24 in a sleeve I25slidably supported in the hub I26 of the gear I3.

There is a pin I21 which extends through the hub and slots I28 in thesleeve I25 and holds the sleeve from rotation. This sleeve has acircular end portion I29 adapted to fit into a recessed plate I39secured in the gear 13 There is a spring I3I in the central recess I32of the sleeve supported at one end by the pin I21 and in the bottom ofthe recess at its forward end. This spring therefore normally tends tomove the sleeve longitudinally to insert the end I29 into the recess inthe plate I30 to lock the gears 13 and I3 together. In the revolution ofthe gear I3 the cam plate I23 will, when the lever H4 is in the positionshown in Fig. 1-9, ride into the slot I24 at the wider forward end whichhas an inclined face I33 and then into engagement with the face I34 andmove the sleeve I25 to the right of the position shown in Fig. 20 andthus release the gear I3 from the gear 13 This is what is termed a onerevolution clutch and it stops the operation of the gear train, thechuck, and the drill carried thereby always in the same rotativeposition and likewise stops the quill I0. Thus the position of thegrinding wheel in its movement toward or from the drill is maintained inconstant operative relationship with the lands of the drill. Uponrelease of the clutch plate 52 from the plate 53, the clutch plate 53,shaft 48 and gears 46, 44 and 39, the shaft 36 and gear 43 may bemanually turned to rotate the chuck to accurately position the lands ofthe drill in respect to the grinding wheel.

- are therefore co-related to produce the desired.

face of the land. When the drill has been located in its desiredposition relative to the gauge, the lever I ll isturned from the fullline position to the dotted line position shown in Fig. 19 withdrawingthe cam plate from possibility of being engaged by the cam face of theslot I24 in the sleeve I25.

The machine will continue to operate in timed relation with the lands ofthe drill as they are presented in sequence through rotation of thedrill for the grinding operation and the grindin operation is automaticand continuous through the forming of the lands on either a two, threeor four lipped drill, in that the speed of rotation of the drill isdependent upon which of the gears ASL-d, Ell-Bl, 5l62 are operated andthis choice of the change speed gears last mentioned is secured by themechanism shown in Fig. 18 heretofore described.

The foregoing description has been confined to the formation of thelands of the drill with surfaces at a uniform angle to the drill axis.It is possible to provide a drill as shown in Figs. 26

and 27 with an angular surface Ml] at the periphery of the land at aless angle to the longitudinal axis of the device than the surface atl4! This may be accomplished with the machine as disclosed by settingthe drill at the angle with the axis thereof as indicated at the leftside of Fig. and after the lands have been ground at the said anglethen, by turning the chuck in the arcuate slot I!) to a less anglerelative to the face of the wheel, grind the surface Hill. A drillhaving the lands ground in the stated manner is often desirable in thatthe surface Mil serves to maintain the drill centered.

The drill may also be ground as shown in Figs. 24 and 25 to form thesurface I42, the surface I43 and the surface I44, By changing the angleof presentation of the drill to the face of the grinding wheel andmaking three successive grinds, first to provide a land at the angle ofthe surface IM and next to cut the remaining surface at the angle Hi3and finally in the third grinding operation to form the surface M2thereon. Drills as indicated in Figs. 22 to 25 inclusive are desirablein some classes of metal in that the drill is more firmly supportedduring the drilling operation.

It is believed evident from the foregoing description, that the variousfeatures and objects of the invention are attained by the structuredescribed namely, that the machine is adapted to form a variable pointin respect to angle of cutting edges to web intersection, variation inthe form of the face of the land in providing various clearance anglesand the formation of a drill at various point angles for varyingcharacters of work, and that various changes may be made in thestructure and relationship of parts forming the machine Withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

Having thus fully described my invention, its utility and mode ofoperation, what I claim and desire to secure by Letters Patent of theUnited States is-- 1. In a machine for grinding twist drills having twoor more lands provided with cutting edges at a predetermined angle tothe web of intersection, a holder for the drill, a grinding wheel forgrinding the same,meansfor varying the angle of presentation of thelands to the face of the wheel to vary the point angle, means forturning the drill during the grinding movement, means for causing thegrinding wheel to feed into the work as the drill is turned whereby theland is ground at a predetermined clearance angle, and means for movingthe wheel laterally of its axis of revolution during the grinding of aland in such man- ,ner that, as the web intersection passes off thecutting face of the grinding wheel, the wheel is moved to its fullextent into the work at the rear of the land to thereby grind the faceof the land to a predetermined depth from the axial point of the drillforward of the web intersection at the time the wheel reaches the limitof its lateral movement in one direction and reaches the limit oflateral movement in the opposite direction as the next land throughrotation of the drill is presented for the grinding operation.

2. In a machine for grinding twist drills, a chuck having jaws forholding the drill, a grinding wheel for grinding the same, said chuckbeing mounted to swing on an arc to present the .drill point at variousangles to the face ofthe grinding wheel to thereby vary the point angleof the drill, a-gear for driving the chuck jaws to rotate the drill, arotatable shaft for the grinding wheel, driving means for the shaft, .arotat able holder for the shaft, the axis of rotation of the holderbeing eccentric to the axis of rotation of the shaft, a gear forrotating the holder, means whereby rotation of the holder for thegrinding wheel shaft causes a reciprocation of the holder and shaft tomove the grinding wheel toward the drill during the grinding of a landto secure a predetermined form of land and to retract from, grindingposition as the next land is brought by rotation of the drill togrinding position, a gear train through which the gear rotating thechuck jaws and gear for reciprocation of the holder for the grindingshaft are actuated in timed relation, a driving gear for the gear train,means for releasing the gear train from the driving gear to permitrotation of the drill holding jaws to rotatively position a land of thedrill with the cutting edge in predetermined relation to the face of thegrinding wheel, said releasing means being operable to connect the geartrain with the driving gear in such manner that subsequent rotation ofthe holder for the grinding wheel shaft and reciprocation thereof is intimed relation to present the successive lands of the drill for thegrinding operation when the grinding wheel is in retracted position.

3. In a machine for grinding twist drills, a chuck having jaws forholding the drill, a grinding wheel for grinding the same, said chuckbeing mounted to swing on an arc to present the drill point at variousangles to the face of the grinding wheel to thereby vary the point angleof the drill, a gear for driving the chuck to rotate the drill, arotatable shaft for the grinding wheel, driving means for the shaft, arotatable holder for the shaft, the axis of rotation of the holder beingeccentric to the axis of rotation of the shaft, a gear for rotating theholder, means whereby rotation of the holder for the grinding wheelshaft causes a reciprocation of the holder and shaft to move thegrinding wheel toward the drill during the grinding of a land to securea predetermined form of land and to retract from grinding position asthe next land is brought by rotation of the drill to grinding position,a gear train through which the gear rotating the chuck and gear forreciprocation of the holder for the grinding shaft are actuated in timedrelation, a driving gear for the gear train, means for releasing thegear train from the driving gear to permit rotation of the drill holdingjaws to rotatively position a land of the drill with the cutting edge inpredetermined relation to the face of the grinding wheel, said releasinmeans being operable to connect the gear train with the driving gear insuch manner that subsequent rotation of the holder for the grindingwheel shaft and reciprocation thereof is in timed relation to presentthe successive lands of the drill for the grinding operation when thegrinding wheel is in retracted position, and means for varying the speedof rotation of the chuck.

4. In a machine for grinding twist drills, a chuck having jaws forholding the drill, a grinding wheel for grinding the same, said chuckbeing mounted to swing on an arc to present the drill point at variousangles to the face of the grinding wheel to thereby vary the point angleof the drill, a gear for driving the chuck jaws to rotate the drill, arotatable shaft for the grinding wheel, driving means for the shaft, arotatable holder for the shaft, the axis of rotation of the holder beingeccentric t the axis of rotation of the shaft, a gear for rotating theholder,

'a cam rotated by the holder for the grinding wheel shaft to causereciprocation of the holder and shaft to move the grinding wheel towardthe drill during the grinding of a land to secure a predetermined formof land and to retract from grinding position as the next land isbrought by rotation of the drill to grinding position, a gear trainthrough which the gear rotating the chuck jaws and gear forreciprocation of the holder for the grinding shaft are actuated in timedrelation, means for varying the throw of the cam to thereby increase ordecrease the extent of feed of the grinding wheel toward the drill, adriving gear for the gear train, means for releasing the gear train fromthe driving gear to permit rotation of the drill holding jaws torotatively position a land of the drill with the cutting edge inpredetermined relation to the face of the grinding wheel, said releasingmeans being operable to connect the gear train with the driving gear insuch manner that subsequent rotation of the holder for the grindingwheel shaft and reciprocation thereof is in timed relation to presentthe successive lands of the drill for the grinding operation when thegrinding wheel is in retracted position, and means for varying the speedof rotation of both the chuck jaws for the drill and the holder for thegrinding wheel shaft in timed relationship.

5. In a machine for grinding drill, a rotatable holder for the drill, agrinding wheel for grinding the same, a shaft for the grinding wheel, ar0- tatable holder for the grinding wheel shaft, means forsimultaneously rotating the holder for the drill and holder for thegrinding wheel shaft in timed relationship, a cam rotatable by theholder for the grinding wheel shaft arranged to reciprocate the saidlast named holder to cause the grinding wheel to feed into the work andto retract therefrom as the successive lands of the drill are brought togrinding position, and means for Varying the throw of the cam to therebyincrease or decrease the extent of feed of the grinding wheel toward thedrill.

EDD C. OLIVER.

